CI: make the brew update temporarily optional. (#2092)

until they decide to fix the brew installation in the macos runners.
see the open issues. eg https://github.com/actions/runner-images/pull/7710

.github/workflows/build.yml

@@ -111,6 +111,7 @@ jobs:
 
       - name: Dependencies
         id: depends
+        continue-on-error: true
         run: |
           brew update
 
@@ -129,6 +130,7 @@ jobs:
 
       - name: Dependencies
         id: depends
+        continue-on-error: true
         run: |
           brew update